Thorium in natural waters

Langmnir D, Herman JS (1980) The mobility of thorium in natural waters at low temperatures. Geochim Cosmochim Acta 44 1753-1766... 

Langmuir D (1978) Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits. Geochim Cosmochim Acta 42 547-569 Langmuir D, Herman JS (1980) The mobility of thorium in natural waters at low temperatures. Geochim Cosmochim Acta 44 1753-1766... 

Unsworth, E. R., Cook, J. M., and Hill, S. J., Determination of uranium and thorium in natural waters with a high matrix concentration using solid-phase extraction inductively coupled plasma mass spectrometry, Anal. Chim. Acta, 442, 141-146, 2001. 

Langmuir, D. Herman, J. S. "The Mobility of Thorium in Natural Waters at Low Temperatures, Geochimica et Cosmochimica Acta 1980,44,1753-1756. 

Figure 3.12 Distribution of thorium complexes versus pH at 2.5°C with LTh = 0.01 /ig/L (a) in pure water (b) with ZSO4 = 100 mg/L. Reprinted from Geochim. et Cosmochim. Acta 44(11), D. Langmuir and J. S. Herman, The mobility of thorium in natural waters at low temperatures, 1753-1766, 1980, with permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, L.K.

Daneshvar, G., Jabbari, A., Yamini, Y. et al. (2009). Determination of uranium and thorium in natural waters by ICP-OES after on-line solid phase extraction and preconcentration in the presence of 2,3-dihydro-9,10-dihydroxy-l,4-anthracenedion, J. Anal. Chem. 64, 602-609. 

Rn-220 is another isotope of radon and belongs to the thorium decay series. Due to its short half life of 55.6 s, reports on its concentrations in those gases and in natural water are still scant. They are also important for a better estimate of our exposure to natural radioactivity and also for the geochemical study of the forma tion of those radon isotopes and their underground movement. 

The bicarbonate ion, HC03, is a prevalent species in natural waters, ranging in concentrations up to 0.8 X 10 3. As was indicated previously, carbonate ions have the ability to form complexes with plutonium. Starik (39) mentions that, in an investigation of the adsorption of uranium, there was a decrease in the adsorption after reaching a maximum, which was explained by the formation of negative carbonate complexes. Kurbatov and co-workers (20) found that increasing the bicarbonate ion concentration in a UXi (thorium) solution decreased the amount of thorium which formed a colloid and became filterable. This again was believed to be caused by the formation of a soluble complex with the bicarbonate. 

Paunescu N. 1986. Determination of uranium and thorium concentration in natural waters. J Radioanal Nucl Chem 104 209-216. 

Gaffney, J. S., Marley, N. S., and Orlandini, K. A., 1992, Evidence for thorium isotopic disequilibria due to organic complexation in natural waters, Environ. Sci. Technol. 26 1248. 

The release of uranium and thorium from minerals into natural waters will depend upon the formation of stable soluble complexes. In aqueous media only Th is known but uranium may exist in one of several oxidation states. The standard potential for the oxidation of U in water according to equation (2) has been re-evaluated as E° - 0.273 0.005 V and a potential diagram for uranium in water at pH 8 is given in Scheme 3. This indicates that will reduce water, while U is unstable with respect to disproportionation to U and U Since the Earth s atmosphere prior to about 2 x 10 y ago was anoxic, and mildly reducing, U " would remain the preferred oxidation state in natural waters at this time. A consequence of this was that uranium and thorium would have exhibited similar chemistry in natural waters, and have been subject to broadly similar redistribution processes early in the Earth s history. Both U " and Th are readily hydrolyzed in aqueous solutions of low acidity. A semiquantitative summary of the equilibrium constants for the hydrolysis of actinide ions in dilute solutions of zero ionic strength has been... 

Naturally occurring oxoanions like SO/ and H2P04 at concentrations representative of those encountered in natural waters can inhibit dissolution and weathering reactions. A very low concentration of inhibitors can often be effective, because it may suffice to block the functional groups of solution-active sites (such as the kink sites). The effect of specifically adsorbable cations on the reduction of dissolution (weathering) rates of minerals is important. A case was documented by Grandstaff (32), who showed that thorium, Pb(II),... 

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